System for the electronic management of photovoltaic cells with adapted thresholds

• US 9,515,517 B2
• Filed: 12/10/2010
• Issued: 12/06/2016
• Est. Priority Date: 12/11/2009
• Status: Active Grant

• Current Assignee: Centre National De La Recherche Scientifique
• Original Assignee: Centre National De La Recherche Scientifique, Total Marketing Services SA (Totalenergies Se)
• Inventors: Alonso, Corinne, Berasategi, Alona, Cabal, Cdric, Estibals, Bruno, Petibon, Stphane, Vermeersch, Marc
• Primary Examiner(s): Zhang, Jue
• Assistant Examiner(s): Jackson, Lakaisha
• Application Number:
  US13/515,082
• Publication Number:
  US 20120256612A1
• Time in Patent Office: 2,188 Days
• Field of Search: 323/272, 323/299, 323/300, 363/65, 307/82
• US Class Current: 1/1
• CPC Class Codes: H01L 31/02021 for solar cells electrical connection means, e.g. junction boxes, specially adapted for structural association with photovoltaic modules H02S40/34
• CPC Class Codes: H02J 7/35 with light sensitive cells
• CPC Class Codes: H02M 1/0032 Control circuits allowing low power mode operation, e.g. in standby mode
• CPC Class Codes: H02M 1/0054 Transistor switching losses periodically suspending operation of switching converter in low power mode H02M1/0035
• CPC Class Codes: H02M 3/1584 with a plurality of power processing stages connected in parallel
• CPC Class Codes: Y02B 70/10 Technologies improving the efficiency by using switched-mode power supplies [SMPS], i.e. efficient power electronics conversion e.g. power factor correction or reduction of losses in power supplies or efficient standby modes
• CPC Class Codes: Y02E 10/56 Power conversion systems, e.g. maximum power point trackers

Abstract

The invention relates to a system for the electronic management of a photovoltaic generator, said system comprising a plurality of n static converters (11, 12, 13) connected in parallel, each converter (11, 12, 13) being electrically connected to at least one photovoltaic cell (10) of the generator. The number of converters connected is determined by comparing the generated power to thresholds P1, P2, . . . , Pn-1 which are defined as the power values substantially at the point of intersection of the performance curves for an increasing number of converters. The invention also relates to a generator comprising said system and to the associated control method.

Claims

1. An electronic control system of a photovoltaic generator having a plurality of photovoltaic cells, the electronic control system comprising:

a plurality of converters coupled in parallel, each of said plurality of converters being electrically selectively coupled to at least one photovoltaic cell of the photovoltaic generator, wherein a number of said plurality of converters coupled to the photovoltaic cells is determined by comparing a variable power generated by the photovoltaic cells to power threshold values (P1, P2, . . . Pn-1) and wherein the threshold values are defined as power values substantially at a point of intersection of at least two of a plurality of efficiency curves, wherein each of said plurality of efficiency curves corresponds to an efficiency curve for a predetermined increasing number of converters such that a threshold value P1 is the intersection between an efficiency curve of one converter and an efficiency curve of two converters, and a threshold value Pn-1 is an intersection between the efficiency curves of n-1 and n converters, wherein a particular one of the threshold values P1, P2, . . . Pn-1 used to determine the number of said plurality of converters coupled to the photovoltaic cells is selected based upon an amount of power generated at an output of the photovoltaic generator, and wherein the threshold values are selected based upon a temperature of said plurality of converters.

2. The system according to claim 1, wherein said plurality of converters is three converters.

3. The system according to claim 2, wherein a first threshold is less than ⅓

of a peak power, preferably between 20% and 33%, advantageously between 23% and 32%.

4. The system according to claim 3, wherein a second threshold is less than ⅔

of a peak power, preferably between 35% and 55%, advantageously between 40% and 50%.

5. The system according to claim 1 wherein the threshold values depend upon an optimal voltage value V_opt of said at least one photovoltaic cell.

6. The system according to claim 1 wherein the threshold values are a function of an input voltage provided to said plurality of converters and wherein the input voltage is an optimal voltage value V_opt of said at least one photovoltaic cell.

7. The system according to claim 1 wherein the threshold values are selected based upon a period of the year and/or sunlight.

8. The system according to claim 1 wherein the threshold values are selected based upon a duty cycle of the plurality of converters.

9. The system according to claim 1 wherein the threshold values are selected based upon an age of the plurality of converters.

10. The system according to claim 1 further comprising a memory management system and wherein the threshold values are stored in said memory management system and wherein the threshold values are subject to change depending upon a measurement of a parameter of the photovoltaic generator.

11. The system according to claim 1 further comprising a device for determining the efficiency curve in function of a power.

12. The system according to claim 1 wherein said plurality of converters are connected in turn.

13. The system according to claim 12 wherein a rotation of said plurality of converters is a variation in the number of converters engaged.

14. The system according to claim 12 wherein a rotation of said plurality of converters depends upon a state of components of said plurality of converters.

15. The system according to claim 1 wherein the electronic control system has threshold values stored therein and wherein the threshold values are subject to change depending upon a measurement of a parameter of the photovoltaic generator.

16. A method of controlling a photovoltaic generator having at least one photovoltaic cell and a plurality of n parallel coupled converters, each of the plurality of n parallel coupled converters being electrically coupled to at least one of the at least one photovoltaic cells, the method comprising:

determining a variable power generated by the at least one photovoltaic cell;

comparing the power generated by the at least one photovoltaic cell with peak power;

comparing the power generated by the at least one photovoltaic cell with one or more power threshold values, wherein the thresholds values are defined as power values substantially at a point of intersection of two or more efficiency curves of a plurality of efficiency curves, wherein each of said plurality of efficiency curves corresponds to an efficiency curve for a predetermined number of converters and such that a threshold value P1 is the intersection between an efficiency curve of one converter and an efficiency curve of two converters, and a threshold value Pn-1 is an intersection between the efficiency curves of n-1 and n converters, wherein a particular one of the threshold values P1, P2, . . . Pn-1 used to determine the number of said plurality of converters coupled to the at least one photovoltaic cell is selected based upon an amount of power generated at an output of the photovoltaic generator, and wherein the threshold values are selected based upon a temperature of said plurality of converters; and

coupling i converters when a measured power value is between Pi and Pi-1 or all the converters if the measured power value is greater than Pn-1.

17. The method of claim 16 further comprising, in response to a measured power value, connecting additional converters when all converters of the plurality of n parallel coupled converters are not connected.

18. The method of claim 17, comprising:

a step of connecting at least a first one of the plurality of n parallel coupled converters to at least one photovoltaic cell; and

a following step of connecting a larger number of the plurality of n parallel coupled converters to at least one photovoltaic cell; and

in response to a need to reduce the number of the plurality of n parallel coupled converters to at least one of the at least one photovoltaic cells, disconnecting the first one of the plurality of n parallel coupled converters.

19. The method of claim 18 further comprising rotating the plurality of n parallel coupled converters in response to a change in measured power value in thresholds between Pi and Pi-1.

20. The method of claim 19 further comprising:

determining one or more of;

a duration of use and/or a number of use of each of the plurality of n parallel coupled converters;

connecting each of the plurality of n parallel coupled converters such that over time, one or more of duration of use and/or the number of use is substantially equal amongst the plurality of n parallel coupled converters.

21. The method of claim 20 for controlling a photovoltaic generator comprising at least one photovoltaic cell and a management system having threshold values stored therein and wherein the threshold values are subject to change depending upon a measurement of a parameter.